Bats and Wind Energy

Renewable energy sources (e.g. solar and wind energy) have received increasing attention in recent years amid concerns about fossil fuels, which have finite availability, detrimental environmental effects, and significant economic and geopolitical costs.  Wind energy certainly has all of the benefits of any alternative energy source, but it does have one significant downside.  Wind-energy facilities can pose a critical threat to birds and bats.  An estimated 850,000 to 1.7 million bats have died from collisions with wind turbines in the United States and Canada since 2000.

Wind-energy facilities on forested ridge tops in the eastern United States are particularly dangerous to bats.  The highest rate of bat fatalities usually occurs from late summer through fall, particularly on warm nights with low wind speeds.  Peak fatalities for many bat species occur during the fall migration and mating season.

The best way to prevent these bat fatalities is to avoid building wind-energy facilities at high-risk sites.  Once a facility is built, the most effective way to protect bats is to stop turbine blades from spinning during predictable, high-risk periods, e.g. when wind speeds are low.  By raising the cut-in speed of turbines (i.e., the wind speed at which turbines begin generating electricity) and feathering blades below cut-in speed, bat fatalities can be reduced by up to 93% with only marginal losses in total annual energy production.  Acoustic deterrents to minimize bat/turbine interactions also have shown promise, but additional research and development are needed.

Bat Conservation International (BCI) joined with the U.S. Fish & Wildlife Service, the American Wind Energy Association (AWEA), and the National Renewable Energy Laboratory (directed by the U.S. Department of Energy) to create the Bats and Wind Energy Cooperative (BWEC) in 2003.  This alliance of non-profit, government, private, and academic organizations is working diligently to eliminate bat fatalities from wind turbines.

We humans have a responsibility to meet our needs in a way that is compatible with bats and all other living creatures.